I only see it having the potential to really be better than ShadowStep in Sub.

In Shadow Dance, if you have Shadow Focus too, you could potentially Cheap Shot target switching between the team. Using this combination of 3 skills, it could make Cheap Shot almost as useful as Shockwave.. albeit with an Energy Cost :/

It make the "Shadowstep + opener" easier, thats all. At least for Sub is nice to have it so it turns it from two buttons to one button click. With Subterfuge it lets you be ready for the rotation with 2 clicks instead of 3 and if the boss moves away you just can easy vanish+C&D and return to normal rotation.

See it as an eazy mode for opening when there is a lot of mobility on the fight.

it seems that with this it becomes impossible for a target to avoid being opened on from stealth, thereby improving your probability of forcing the use of a pvp trinket. It will be far easier to get a sap and then immediately open on another target without losing time on the sap cc.

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I only see it having the potential to really be better than ShadowStep in Sub.

In Shadow Dance, if you have Shadow Focus too, you could potentially Cheap Shot target switching between the team. Using this combination of 3 skills, it could make Cheap Shot almost as useful as Shockwave.. albeit with an Energy Cost :/

A night elf sub rogue starting from stealth will get 12 uses of shadowstep over the course of 5 minutes.

Cloak and dagger has:
Initial Opener
Up to four vanishes.
Up to three shadowmelds.
Up to five dances.

That's up to 13- and many of them can be back to back, and doesn't count the fact that dance can be used for multiple ones.

I'm honestly not sure how popular it will be. You can't, for instance, sap someone and immediately shadowstep a focus- meaning you may get destealthed during that global, or CCed (for instance, an aoe fear would be a counter there). It has a lot of synergy with subterfuge- to the point where it's very likely you'll want to take subterfuge if you take cloak and dagger at all.

Shadowstep seems like it will be the most popular talent in that tier. Cloak and Dagger represents a different kind of power though.

The "hype" for Cloak and Dagger was mostly generated when it broke roots. Being able to continuously break roots during every GCD of Shadowdance just sounds crazy. Given that it doesn't, it still has uses, as Verain points out above, but the "hype" is mostly gone, and there are serious discussions comparing ShS to Cloak and Dagger, by opponent team, from what I've read as an outsider to PvP.

Call me crazy, but I just can't see how tying our only real mobility to all of our dps/control/defensive moves is the best idea. And you are just as peelable during dance with that as you are on live since the only thing it might help with is a difference in movement speed. The only real gains I see are that it would be almost a guaranteed opener (warlock crap can still easily hit you though) and you could turn your major dps burst cd into a major cc the other team cd (which obviously has the rather high cost of massively gimping your burst potential for a minute), and those aren't enough for me to drop step.